go_back.onclick = function () {
  history.back();
};
go_forward.onclick = function () {
  history.forward();
};
go_a.onclick = function () {
  location.href =
    "http://127.0.0.1:5500/JavaScript%E5%88%9D%E8%AF%86/BOM/A.html";
};
go_b.onclick = function () {
  location.href =
    "http://127.0.0.1:5500/JavaScript%E5%88%9D%E8%AF%86/BOM/B.html";
};
